This invention relates to providing a system for improved radiators. More particularly this invention relates to providing a system for controlled partial shutdown and restart of radiator systems in extreme-cold environments. In extreme-cold environments thermal control is necessary for the function of electronics as well as life-support systems, particularly for manned space flight. However, radiator systems used for this thermal control may encounter stagnation of a thermal transfer fluid, and potential freezing, when thermal-emission-needs drop low due to shutdown of some waste-heat-generating subsystems.
When a radiator system does not have sufficient heat entering the system, eventually the thermal fluid cools to a point where stagnation occurs, which can prevent fluid flow through a part or all of the radiator system. Once full stagnation occurs, it becomes difficult to recover normal operation of the radiator system when the waste heat generated increases from the startup of additional waste-heat-generating systems. Further, should stagnation of thermal fluid remain too long, freezing may occur, potentially causing damage to the radiator system.
For the reasons above radiator system designs, for use in extreme-cold environments, have paid particular attention to preventing the stagnation of the thermal fluid by either designing the radiator system to handle a specific heat load (not allowing variation) or using a fluid with a low freezing temperature. However, this is problematic when thermal emission needs vary dramatically within an overall system having multiple uses with multiple configurations of waste-heat-generating subsystems, since in one configuration the waste heat generated may be minimal and in a second configuration the waste heat generated may be substantially larger. Further, thermal fluids having low freezing temperatures comprise toxic and/or flammable substances which are dangerous to use in manned environments. A radiator system is needed which can vary the heat transported in a controlled manner, thereby avoiding the risks currently associated with stagnation of the thermal fluid, and which uses thermal fluids safe for use within manned environments.